DESCRIPTION: (Applicant's Abstract) Addiction is a condition in which motivation narrows to focus on drug rewards, largely at the expense of a person's life and the more natural pleasures~of life. Of these pleasures, sexual activity is often among the first to be disrupted by chronic drug use. Yet, many drugs of abuse are considered "prosexual" in that they stimulate sexual desire, arousal, and performance directly, or produce a general disinhibition that prompts individuals to engage in promiscuous or unsafe sexual activity. This latter effect increases the chances of contracting or spreading sexually transmitted diseases and HIV. Curiously, much of our knowledge of the effects of drugs of abuse on sexual behavior comes from clinical anecdotes and case reports; very few experimental studies have been conducted in humans or animals regarding the short- and long-term effects of these drugs on sexual function. The goal of the present research is to provide a systematic account of the inhibitory and disinhibitory effects of these drugs by examining the short- and long term effects of the psychomotor stimulants amphetamine and cocaine, and the central nervous system depressant, heroin, on appetitive and consummatory measures of sexual behavior in female and male rats. Sexual motivation and performance of sexually experienced and inexperienced male and female rats will be assessed during periods of drug intoxication, withdrawal, and drug challenge. If tolerance or sensitization to the inhibitory or facilitative effects of these drugs occurs, then subsequent studies will examine whether it is contingent upon animals attempting to display sexual activity during periods of intoxication, rather than on drug exposure per se. The disinhibitory effects of these drugs will be examined using behavioral I paradigms in which primary or conditioned inhibition of sexual behavior in male or female rats is established prior to the administration of these drugs. This research will generate new animal models of the inhibitory and disinhibitory effects of drugs on sexual behavior, and will help to determine the conditions under which drug taking contributes to risky sex practices that hasten the spread of sexually transmitted diseases and HIV.